Valve timing control apparatus for internal combustion engine and internal combustion engine using the same

ABSTRACT

Provided is a novel valve timing control apparatus capable of reducing an axial length and of reducing a thickness of a housing. A valve timing control apparatus for an internal combustion engine includes a timing pulley to which a rotational force is transmitted from a crankshaft via a timing belt, a housing configured to be rotated by the timing pulley and including a plurality of shoes provided on an inner peripheral surface thereof, and a vane rotor relatively rotatably contained inside the housing and configured to be rotated in synchronization with a camshaft. The vane rotor includes a vane forming a retard angle oil chamber and an advance angle oil chamber inside the housing in cooperation with the plurality of shoes. A predetermined interval is provided between an outer peripheral portion of the housing and an inner peripheral portion of the timing pulley. An outer peripheral portion of a housing main body of the housing and the inner peripheral portion of the timing pulley are coupled with each other via a plurality of coupling beam portions with intervals in a circumferential direction. The housing main body, the timing pulley, and the plurality of coupling beam portions are integrally formed.

TECHNICAL FIELD

The present invention relates to a valve timing control apparatus that variably controls an opening/closing timing of an engine valve, which is an intake valve or an exhaust valve of an internal combustion engine, according to an operation state, and an internal combustion engine using this valve timing control apparatus.

BACKGROUND ART

As a conventional valve timing control apparatus, a vane-type valve timing control apparatus is well known. This vane-type valve timing control apparatus includes a housing to which a rotational force is transmitted from a crankshaft, and a vane member rotatably contained inside this housing and fixed at an end portion of the camshaft. An advance angle oil chamber and a retard angle oil chamber are formed between a plurality of shoes each protruding inward from a diameter direction on an inner peripheral surface of the housing, and a plurality of vanes of the vane member.

Then, the vane-type valve timing control apparatus is configured to variably control an opening/closing timing of an intake vale or an exhaust valve by selectively supplying hydraulic oil discharged from an electric pump or a mechanical pump to any of the advance angle oil chamber and the retard angle oil chamber according to an operation state of an engine to rotate the vane member in a forward direction or a reverse direction by a driving hydraulic pressure of this hydraulic oil and then holding the vanes at predetermined positions.

Such a vane-type valve timing control apparatus should have a small size because being mounted on an internal combustion engine in an engine room, and reducing an axial size of the valve timing control apparatus is also one of measures therefor. Some of conventional valve timing control apparatuses have failed to achieve the reduction in the axial size because a timing pulley and the housing forming the advance angle oil chamber and the retard angle oil chamber are disposed while being axially arranged.

Therefore, various techniques have been developed and proposed to meet this requirement of the reduction in the axial size of the valve timing control apparatus. For example, Japanese Patent Application Public Disclosure No. 2012-132404 (PTL 1) proposes a valve timing control apparatus configured in the following manner. An annular timing pulley is disposed so as to partially overlap an outer peripheral side of a housing, and protruding coupling portions are formed so as to protrude inward at even intervals on an inner peripheral side of the timing pulley. The protruding coupling portions are coupled and fixed with use of bolts to a rear plate fixed to the housing to form an advance angle oil chamber and a retard angle oil chamber.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Application Public Disclosure No. 2012-132404

SUMMARY OF INVENTION Technical Problem

Then, in the valve timing control apparatus discussed in PTL 1, the timing pulley is configured to be fixed to the rear plate via the protruding coupling portions. This means that an outer peripheral portion of the housing is configured in a similar manner to the conventional configuration, so that the outer peripheral portion of the housing should have a great thickness to prevent or reduce deformation of the housing when the vane abuts against the shoe of the housing. Therefore, this valve timing control apparatus still leaves unsolved a problem of increases in a diameter and a weight of the housing.

An object of the present invention is to provide a novel valve timing control apparatus capable of reducing the thickness of the housing and an internal combustion engine using this valve timing control apparatus.

Solution to Problem

According to one aspect of the present invention, a timing pulley is disposed on an outer peripheral portion of a housing forming an advance angle oil chamber and a retard angle oil chamber with a predetermined interval. Then, an outer peripheral portion of a housing main body of the housing and an inner peripheral portion of the timing pulley are coupled with each other via a plurality of coupling beam portions with intervals in a circumferential direction. Further, the housing, the timing pulley, and the plurality of coupling beam portions are integrally formed.

According to the one aspect of the present invention, the outer peripheral portion of the housing and the inner peripheral portion of the timing pulley are connected via the coupling beam portions and integrally formed, and thus the outer peripheral portion of the housing is reinforced by the coupling beam portions, so that the outer peripheral portion of the housing can have a thin thickness.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating one embodiment of a hydraulic circuit of a valve timing control apparatus according to the present invention.

FIG. 2 is an exploded perspective view illustrating a first embodiment of the valve timing control apparatus according to the present invention.

FIG. 3 illustrates an operation with a valve timing controlled toward a retard angle side according to the first embodiment.

FIG. 4 illustrates an operation with the valve timing controlled toward an advance angle side according to the first embodiment.

FIG. 5 is a vertical cross-sectional view illustrating a state locked by a lock mechanism provided to the first embodiment.

FIG. 6 illustrates an operation with the valve timing controlled toward the retard angle side according to a second embodiment of the present invention.

FIG. 7 illustrates an operation with the valve timing controlled toward the advance angle side according to the second embodiment of the present invention.

FIG. 8 illustrates an operation with the valve timing controlled toward the retard angle side according to a third embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail with reference to the drawings, but the present invention shall not be limited to the following embodiments and the scope thereof shall include even various modifications and application examples within the technical idea of the present invention.

First Embodiment

In the following description, a valve timing control apparatus for an internal combustion engine according to a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

The valve timing control apparatus illustrated in FIG. 1 is disposed on an upper surface of a cylinder head of an engine, and functions to control an opening/closing timing of an engine valve. Then, the valve timing control apparatus includes a timing pulley 1, a camshaft 2, a phase conversion mechanism 3, and a hydraulic circuit mechanism 4. The timing pulley 1 is rotationally driven by a crankshaft rotatable according to activation of a not-illustrated piston of the engine via a timing belt. The camshaft 2 is provided rotatably relative to the timing pulley 1. The phase conversion mechanism 3 is disposed between the timing pulley 1 and the camshaft 2, and converts a relative rotational position between them. The hydraulic circuit mechanism 4 supplies hydraulic oil for activating the phase conversion mechanism 3.

Now, in the present embodiment, the camshaft 2 is an intake-side camshaft, and the phase conversion mechanism 3 functions to control an opening/closing timing of an intake valve. Needless to say, the phase conversion mechanism 3 can also function to control an opening/closing timing of an exhaust valve by being be mounted on an exhaust-side camshaft, and further, can also function to control the opening/closing timings of both the intake valve and the exhaust valve.

The camshaft 2 is rotatably supported by the not-illustrated cylinder head via a cam bearing, with a plurality of driving cams integrally provided at predetermined positions on an outer peripheral surface thereof and a female screw hole 2 b formed in an internal axial direction of one end portion 2 a. The plurality of driving cams activates the intake vale to open it via a valve lifter. A cam bolt 6, which will be described below, is threadably engaged with the female screw hole 2 b.

As illustrated in FIGS. 2 and 3, the phase conversion mechanism 3 includes a cylindrical housing 5, a vane member 7, and four retard angle hydraulic chambers 9 and four advance angle hydraulic chambers 10. The housing 5 is disposed at the one end portion of the camshaft 2. The vane member 7 is fixed to the one end portion of the camshaft 2 from an axial direction with use of the cam bolt 6, and is rotatably contained in the housing 5. The four retard angle hydraulic chambers 9 and the four advance angle chambers 10 are formed in the housing 5, and are defined by four shoes 8 held on an inner peripheral surface of the housing 5 and four vanes 22 to 25 of the vane member 7.

The housing 5 includes an approximately cylindrical housing main body 11, and a front plate 12 and a rear plate 13 closing front and rear opening ends of the housing main body 11, respectively. The housing main body 11, the front plate 12, and the rear plate 13 are integrally coupled with one another by being fastened together with use of four bolts 14 from the axial direction.

Further, the four shoes 8 are integrally provided in a protruding manner on an inner peripheral surface of the housing main body 11 at positions arranged at approximately even intervals on a circumference. Each of these shoes 8 is formed into generally U shape, and a seal member 28 is fittedly attached in a seal groove 57 formed at a distal end of each of the shoes 8 along the axial direction. The seal member 28 is in sliding contact with a peripheral surface 7 c of the vane member 7, and has a generally squared U shape. Further, a bolt insertion hole 17, through which each of the bolts 14 is inserted, is formed in a penetrating manner in an inner axial direction on a base portion side of each of the shoes 8.

As illustrated in FIGS. 1 and 2, the front plate 12 is formed into a relatively thin disk shape, and a large-diameter hole 12 a, through which the cam bolt 6 is inserted, is pierced at a center thereof. Further, four bolt holes 12 c, through each of which each of the bolts 14 is inserted, are formed in a penetrating manner at positions arranged at approximately even intervals in a circumferential direction on an outer peripheral side.

A support hole 19 is pierced at a center of the rear plate 13. The camshaft 2 is rotatably supported by being inserted through the support hole 19. Further, female screw holes 13 a are formed at positions arranged at approximately even intervals in the circumferential direction on an outer peripheral side. Male screws at distal end portions of the above-described bolts 14 are threadably engaged with the female holes 13 a. Further, a positioning pin 13 b is provided at a part of the rear plate 13, and is engaged with a not-illustrated positioning hole provided on the housing 5, thereby positioning the housing 5 and the rear plate 13.

As illustrated in FIGS. 2 and 3, the vane member 7 includes a vane rotor 21 and the four vanes 22 to 25. The vane rotor 21 is fixed to the one end portion 2 a of the camshaft 2 from the axial direction with use of the cam bolt 6 inserted through the insertion hole 7 a from the axial direction. The vanes 22 to 25 are provided in a radially protruding manner at positions arranged at approximately even intervals in the circumferential direction on an outer peripheral surface of this vane rotor 21.

The vane rotor 21 is supported so as to be rotatable while sliding on the seal member 28 fittedly attached on a top surface of the distal end portion of each of the shoes 8, and includes four retard angle-side oil holes 20 formed in an inner radial direction and four advance angle-side oil grooves 27 formed at a rear plate-side end portion as illustrated in FIGS. 2, 3, and 4. The retard angle-side oil holes 20 are each in communication with each of the retard angle hydraulic chambers 9. The advance angle-side oil grooves 27 are each in communication with each of the advance angle hydraulic chambers 10.

Each of the vanes 22 to 25 is disposed between the shoes 8, and the seal member 28 is fittedly attached in the seal groove 57 axially formed at each of distal surfaces of the vanes 22 to 25. The seal member 28 is in sliding contact with an inner peripheral surface 11 a of the housing main body 11, and has the generally squared U shape in the axial direction. Further, as illustrated in FIGS. 2, 3, and 4, each of the vanes 22 to 25 has a different circumferential width from one another, and one of the vanes, namely, the vane 22 is formed so as to have a maximum width, which allows the vane 22 to contain therein a lock piston, which will be described below. The remaining vanes 23 to 25 may have the same widths or may have different widths. However, it is effective to use a thicker width for the vane 24, which is located on an opposite side from the vane 22, than the vanes 23 and 25 to establish weight balance with respect to the vane 22.

The vane 22 having the maximum width is configured to, in the case where the vane member 7 controls the intake valve as illustrated in FIG. 3, when being rotated maximally in a counterclockwise direction, abut at a distal edge thereof against a side surface of the shoe 8 facing the vane 22 to regulate a rotation more than that, thereby adjusting a relative rotational conversion angle between the housing 5 and the vane member 7. Further, the vane 22 having the maximum width includes a protruding portion 200 b. In the case where the vane member 7 controls the intake valve as illustrated in FIG. 4, when being rotated maximally in a clockwise direction, the protruding portion 200 b regulates a rotation more than that by abutting against the side surface of the shoe 8 facing the vane 22.

Further, a lock mechanism is provided between the vane 22 having the maximum width and the rear plate 13. The lock mechanism constrains a free rotation of the vane member 7. The lock mechanism includes a lock piston 30, a lock hole 31, and an engagement and disengagement mechanism. The lock piston 30 is slidably contained in a sliding movement hole 29 formed in a penetrating manner in an inner axial direction of the vane 22, and is provided movably toward or away from the rear plate 13 side. The lock hole 31 is formed at a predetermined circumferential position on an inner end surface of the rear plate 13, and a distal end portion 30 a of the lock piston 30 is engaged therewith by moving forward or being disengaged therefrom by moving backward. The engagement and disengagement mechanism causes the lock piston 30 to be engaged with or disengaged from the lock hole 31 according to a start state of the engine.

As illustrated in FIG. 5, the lock piston 30 is formed into a cylindrical pin shape and also includes the distal end portion 30 a formed into a generally conical shape, thereby being formed into a shape easily engaged into the lock hole 31. As illustrated in FIG. 1, a rectangular cutout groove 7 b is formed on the front plate 21 side of the sliding movement hole 29, and the cutout groove 7 b is configured to function as an air vent for constantly ensuring an excellent sliding movement of the lock piston 30 in a range where the vane member 7 is rotated by being in communication with outside air.

Further, the lock hole 31 is set in such a manner that the vane member 7 is located on a retard angle side or an advance angle side where the relative conversion angle between the housing 5 and the vane member 7 matches an optimum conversion angle at the time of the start of the engine when the lock piston 30 is engaged therewith, as illustrated in FIGS. 3 and 4.

As illustrated in FIG. 5, the engagement and disengagement mechanism is elastically mounted between a rear end portion of the lock piston 30 and an inner end surface of the front plate 12, and includes a coil spring 32 and release hydraulic circuits 54 and 55. The coil spring 32 biases the lock piston 30 in a forward direction. The release hydraulic circuits 54 and 55 cause the lock piston 30 to move backward by supplying a hydraulic pressure into the lock hole 31. These release hydraulic circuits 54 and 55 are configured in such a manner that hydraulic oil selectively supplied into each of the retard angle oil chamber 9 and the advance angle oil chamber 10 is introduced via a predetermined oil hole.

Referring back to FIG. 1, the hydraulic circuit mechanism 4 functions to selectively supply the hydraulic oil to the advance angle oil chamber 9 and the retard angle oil chamber 10 or discharge the hydraulic oil from inside the advance angle oil chamber 9 and the retard angle oil chamber 10, and includes a retard angle-side passage 36, an advance angle-side passage 37, an oil pump 39, and a drain passage 40 in the case where the intake valve is controlled. The retard angle-side passage 36 is in communication with each of the retard angle-side oil holes 20. The advance angle-side passage 37 is in communication with each of the advance angle-side oil grooves 27. The oil pump 39 selectively supplies the hydraulic oil to each of these passages 36 and 37 via an electromagnetic switching valve 38. The drain passage 40 is selectively brought into communication with the retard angle-side passage 36 and the advance angle-side passage 37 via the electromagnetic switching valve 38. The oil pump 39 functions to introduce the hydraulic oil from a hydraulic oil container (an oil pan) 41, and the drain passage 40 functions to return the hydraulic oil to the hydraulic oil container 41.

The retard angle-side passage 36 and the advance angle-side passage 37 are in communication with each of the oil grooves 27 and each of the oil holes 20 via oil passage holes 36 a and 37 a and grooved grooves 36 b and 37 b formed along a radial direction and the axial direction inside the camshaft 2.

The electromagnetic switching valve 38 is a bidirectional valve, and is configured to perform control of selectively switching the retard angle-side passage 36 and the advance angle-side passage 37, and a discharge passage 39 a of the oil pump 39 and the drain passage 40 according to an output signal from a not-illustrated controller.

The controller is configured in such a manner that an internal computer thereof detects a present operation state of the engine by inputting operation information signals from various kinds of sensors, such as a not-illustrated crank angle sensor, airflow meter, water temperature sensor, and throttle valve opening degree sensor, and outputs a control current to an electromagnetic coil of the electromagnetic switching valve 38 according to the operation state of the engine.

The valve timing control apparatus configured in this manner functions to perform the following operation. First, when the engine is started, the lock piston 30 is engaged into the lock hole 31 in advance, thereby constraining the vane member 7 at the position on the retard angle side optimum for the start, as illustrated in FIG. 3. Therefore, when an ignition switch is operated to be turned on and the engine is started, excellent startability can be acquired by smooth cranking.

Then, in a predetermined load region after the engine is started, the controller supplies the control current to the electromagnetic coil of the electromagnetic switching valve 38. This power supply establishes the communication through the advance angle-side passage 37, and, at the same time, establishes the communication between the retard angle-side passage 36 and the drain passage 40 in the case where the intake valve is controlled from the discharge passage 39 a of the oil pump 39.

Therefore, the hydraulic oil discharged from the oil pump 39 flows into the advance angle oil chamber 10 via the advance angle-side passage 37 to increase a pressure in the advance angle oil chamber 10, while the hydraulic oil in the retard angle oil chamber 9 is discharged from the drain passage 40 into the oil pan 41 via the retard angle-side passage 36 to reduce a pressure in the retard angle oil chamber 9.

At this time, the hydraulic oil delivered into the advance angle oil chamber 10 flows into the lock hole 31, thereby causing the lock piston 30 to move backward to thus exit from the lock hole 31. As a result, the free rotation of the vane member 7 is secured. Therefore, the vane member 7 is rotated in the clockwise direction as illustrated in FIG. 4 according to an increase in a volume of the advance angle oil chamber 10. Therefore, the relative rotational angle of the camshaft 2 relative to the timing pulley 1 is converted into the advance angle side.

On the other hand, when the engine transitions to another load region, the supply of the control current from the controller to the electromagnetic switching valve 38 is stopped, which establishes the communication between the discharge passage 39 a and the retard angle-side passage 36, and, at the same time, establishes the communication between the advance angle-side passage 37 and the drain passage 40. As a result, the hydraulic oil in the advance angle oil chamber 10 is discharged to reduce the pressure in the advance angle oil chamber 10, and the hydraulic oil is supplied into the retard angle oil chamber 9 to increase the pressure in the retard angle oil chamber 9. At this time, the hydraulic pressure is supplied from the retard angle oil chamber 9 into the lock hole 31, so that the lock piston 30 is kept pulled out of the lock hole 31. Therefore, the vane member 7 is rotated relative to the housing 5 in the counterclockwise direction as illustrated in FIG. 3 to convert a relative rotational phase relative to the timing pulley 1 into the retard angle side.

The present embodiment is characterized by an addition of a configuration that will be described below to the valve timing control apparatus configured in this manner

As illustrated in FIGS. 2 and 3, an outer shape of the housing 5 is a generally circular shape, and an outer shape of the timing pulley 1 is also formed into a generally annular shape in conformity thereto. External teeth, which are meshed with the timing belt, are formed on an outer peripheral side of the timing pulley. Then, the timing pulley 1 is located outside the outer peripheral portion of the housing 5, and the housing 5 and the timing pulley 1 are divided and separated with a predetermined distance L (refer to FIG. 3) generated therebetween.

An inner peripheral side of the timing pulley 1 and an outer peripheral side of the housing main body 11 are coupled and integrated with each other via four coupling beam portions 100 a to 100 d. Therefore, the housing main body 11 and the timing pulley 1 are not coupled with each other and space regions Sr are formed in circumferential intervals between the individual coupling beam portions 100 a to 100 d.

The housing main body 11, the timing pulley 1, and the coupling beam portions 100 a to 100 d can be integrally formed by a processing method such as cutting, casting, or drawing aluminum, an aluminum alloy, or the like. Further, they can be integrally formed by sintering metallic powder, such as iron powder, aluminum powder, or ferrous metallic powder. Further, they can also be integrally formed from resin.

In the present embodiment, the housing main body 5, the timing pulley 1, and the coupling beam portions 100 a to 100 d are integrally formed by sintering the ferrous metallic powder. Manufacturing them by sintering the ferrous metallic powder in this manner facilitates formation of components of the valve timing control apparatus having a complicated shape like the present embodiment.

As illustrated in FIG. 1, the timing pulley 1 is disposed so as to overlap the housing main body 11 outside the outer peripheral portion of the housing main body 11. In other words, the timing pulley 1 is arranged so as to be located between projection surfaces defined by radially extending an outer surface of the front plate 12 and an outer surface of the rear plate 13 with the front plate 12, the housing main body 11, and the rear plate 13 mounted together.

Therefore, an axial length of the timing pulley 1 can be ignored because the timing pulley 1 is located between the projection surfaces defined by radially extending the outer surface of the front plate 12 and the outer surface of the rear plate 13, so that an axial length of the valve timing control apparatus can be reduced by an amount corresponding thereto.

In the present embodiment, the timing pulley 1 and the housing main body 11 are integrally formed as illustrated in FIG. 1, so that an axial length Lt of the timing pulley 1 and an axial length Lh of the housing main body 11 are the same as each other. The length Lt of the timing pulley 1 and the length Lh of the housing main body 11 are the same as each other in this manner, which can simplify a mold structure in a case where they are formed by the sintering.

Further, axial lengths of the four coupling beam portions 100 a to 100 d connecting the inner peripheral side of the timing pulley 1 and the outer peripheral side of the housing main body 11 to each other may be set to the same sizes as the length Lt of the timing pulley 1 and the length Lh of the housing main body 11. This setting can simplify the mold structure in the case where they are formed by the sintering.

However, in the present embodiment, the axial lengths of the four coupling beam portions 100 a to 100 d are set to shorter sizes than the length Lt of the timing pulley 1 and the length Lh of the housing main body 11. This setting brings about an effect of being able to reduce a weight due to the coupling beam portions 100 a to 100 d, thereby eventually being able to reduce a weight of the valve timing control apparatus after the manufacturing thereof is completed. Further, the coupling beam portions 100 a to 100 d are arranged to allow a stress to be less concentrated by being coupled around axially central portions of the inner peripheral portion of the timing pulley 1 and the outer peripheral portion of the housing main body 11, and having arcuate shapes around these coupling portions.

As illustrated in FIGS. 3 and 4, the coupling beam portions 100 a to 100 are disposed in regions between the positions where the individual shoes 8 are disposed, and coupled to portions of the housing main body 11 having thin thicknesses. The four shoes 8 are large in cross-sectional area and therefore also secure sufficient mechanical strength, but the outer peripheral regions between the four shoes 8 have the thin thicknesses and therefore are insufficient in mechanical strength. Conventionally, this problem has been deal with by increasing the thicknesses of these regions.

On the other hand, in the present embodiment, the coupling beam portions 100 a to 100 d are provided in the outer peripheral regions between the four shoes 8, and therefore the mechanical strength of the outer peripheral regions between the four shoes 8 can be enhanced due to the coupling beam portions 100 a to 100 d. Therefore, the present embodiment allows the outer peripheral portion of the housing main body 11 to have a thin thickness, thereby succeeding in bring about an effect of being able to reduce the diameter of the housing 5 or being able to reduce the weight.

In the present embodiment, the four coupling beam portions 100 a to 100 d are provided in the regions between the four shoes 8 that are sandwiched by the space regions Sr, which improves weight distribution of the individual shoes 8 and the coupling beam portions 100 a to 100 d and achieves evenness of the weight as a whole with the timing pulley 1, the front plate 12, the housing main body 11, and the rear plate 13 mounted together, thereby leading to a success in improvement of a weight balance.

Further, generally, the vane 22 having the maximum width where the lock piston 30 is disposed is heavier in weight than the other vanes 23 to 25, and this means that a center of gravity on a plane orthogonal to the axial direction is necessarily offset toward one side where the vane 22 having the maximum width is located, with the timing pulley 1, the front plate 12, the housing main body 11, and the rear plate 13 mounted together. The center of gravity excessively offset toward one side impedes the rotational motion, and therefore the center of gravity should be placed as close to the rotational center as possible.

One conceivable measure therefor is to provide a thicker portion at an opposite position from the vane 22 having the maximum width (an opposite position of the rotational center with respect to the vane 22 having the maximum width), but employing such a structure raises a problem of an increase in a total weight due to the thicker portion.

On the other hand, in the present embodiment, the coupling beam portions 100 b and 100 d are disposed closer to the coupling beam portion 100 c side in addition to the disposition of the coupling beam portion 100 c on the approximately opposite side, which allows the center of gravity to be placed as close to the rotational center as possible without providing the thicker portion, thereby preventing or cutting down the increase in the weight. In this manner, the present embodiment allows the coupling beam portions 100 b to 100 d to have a balance improvement function of improving the weight balance, in addition to the function of mechanically reinforcing the outer peripheral portion of the housing main body 11.

Further, there is such a problem that the timing pulley 1 has a large area due to its geometry and has a heavy weight relative to the housing 5. Therefore, in the present embodiment, the valve timing control apparatus is configured in such a manner that the space regions Sr are formed by the disposition of the coupling beam portions 100 a to 100 d at the predetermined intervals in the circumferential direction. This configuration allows the valve timing control apparatus to achieve an effect of being able to reduce the weight of the timing pulley 1.

Further, the timing pulley 1 and the housing main body 11 are integrally formed via the coupling beam portions 100 a to 100 d, which eliminates a necessity of coupling and fixing the timing pulley and the rear plate with use of the bolts like PTL 1, thereby never raising a problem of an increase in the number of components and thus an increase in the number of processes for mounting the components according thereto.

Further, when the valve timing control apparatus is mounted on the camshaft, the valve timing control apparatus can be mounted on the camshaft by holding the timing pulley 1 since the housing 5 and the timing pulley 1 are integrated, so that the present embodiment also brings about an effect of facilitating centering at the time of the mounting.

In the above-described manner, according to the present embodiment, the timing pulley is disposed on the outer peripheral portion of the housing forming the advance angle oil chambers and the retard angle oil chambers with the interval, and the outer peripheral portion of the housing and the timing pulley are coupled with each other via the plurality of coupling beam portions with the interval in the circumferential direction. Further, the housing, the timing pulley, and the coupling beam portions are integrally formed from metal.

According to this configuration, the outer peripheral portion of the housing and the timing pulley are connected via the coupling beam portions and are integrally formed, and thus the outer peripheral portion of the housing is reinforced by the coupling beam portions, so that the outer peripheral portion of the housing can have a thin thickness.

Second Embodiment

Next, a valve timing control apparatus according to a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. The present embodiment is basically similar to the first embodiment, and therefore similar functions and effects to the first embodiment will not be described below.

FIG. 6 illustrates a maximum retard angle state, and FIG. 7 illustrates a maximum advance angle state. A retard angle-side stopper surface 200 a and an advance angle-side stopper surface 200 b are formed on both side surfaces of the vane 22 having the maximum width. Then, a retard angle-side abutment surface 300 a is formed on a wall surface of a shoe 8 r which the retard angle-side stopper surface 200 a hits and abuts against, and an advance angle-side abutment surface 300 b is formed on a wall surface of a shoe 8 a which the advance angle-side stopper surface 200 b hits and abuts against.

Then, when the valve member 7 is controlled to the maximum retard angle position illustrated in FIG. 6 with the valve timing control apparatus activated, the retard angle-side stopper surface 200 a of the vane 22 having the maximum width hits the retard angle-side abutment surface 300 a of the shoe 8 r with a strong force. At this time, deformation occurs in such a manner that the outer peripheral portion of the housing main body 11 on the opposite side from the retard angle-side abutment surface 300 a is rotated around the bolt 14 in the bolt insertion hole 17 provided at the shoe 8 r.

Similarly, when the vane member 7 is controlled to the maximum advance angle position illustrated in FIG. 7 with the valve timing control apparatus activated, the advance angle-side stopper surface 200 b of the vane 22 having the maximum width hits the advance angle-side abutment surface 300 b of the shoe 8 a with a strong force. At this time, deformation occurs in such a manner that the outer peripheral portion of the housing main body 11 on the opposite side from the advance angle-side abutment surface 300 b is rotated around the bolt 14 in the bolt insertion hole 17 provided at the shoe 8 a.

Therefore, in the present embodiment, the coupling beam portion 100 d is provided around a connection region Cr1 of the space region Sr in proximity to an opposite surface of the shoe 8 r from the retard angle-side abutment surface 300 a as illustrated in FIG. 6. In other words, the coupling beam portion 100 d is provided on one side closer to a shoe 8 r with respect to a circumferential center between the opposite side surface 300 c of the shoe 8 r from the retard angle-side abutment surface 300 a and the shoe 8 c facing the side surface 300 c in the circumferential direction. In this case, the coupling beam portion 00 d may be disposed so as to partially overlap the opposite surface of the shoe 8 r from the retard angle-side abutment surface 200 b as viewed in the circumferential direction.

Similarly, the coupling beam portion 100 b is arranged so as to be provided around a connection region Cr2 of the space region Sr in proximity to an opposite surface of the shoe 8 a from the advance angle-side abutment surface 300 b as illustrated in FIG. 7. In other words, the coupling beam portion 100 b is provided on one side closer to the shoe 8 a with respect to a circumferential center between the opposite side surface 300 d of the shoe 8 a from the advance angle-side abutment surface 300 b and a shoe 8 d facing the opposite side surface 300 d in the circumferential direction. In this case, the coupling beam portion 00 b may also be disposed so as to partially overlap the opposite surface of the shoe 8 a from the advance angle-side abutment surface 300 b as viewed in the circumferential direction.

Therefore, when the vane member 7 is controlled to the maximum retard angle position illustrated in FIG. 6, the retard angle-side stopper surface 200 a of the vane 22 having the maximum width hits the retard angle-side abutment surface 300 a of the shoe 8 r with the strong force. At this time, the deformation occurs in such a manner that the outer peripheral portion of the housing main body 11 on the opposite side from the retard angle-side abutment surface 300 a is rotated around the bolt 14 in the bolt insertion hole 17 provided at the shoe 8 r, but this deformation is received by the coupling beam portion 100 d, which leads to prevention or reduction of the deformation of the outer peripheral portion of the housing main body 11.

Similarly, when the vane member 7 is controlled to the maximum advance angle position illustrated in FIG. 7, the advance angle-side stopper surface 200 b of the vane 22 having the maximum width hits the advance angle-side abutment surface 300 b of the shoe 8 a with the strong force. At this time, the deformation occurs in such a manner that the outer peripheral portion of the housing main body 11 on the opposite side from the advance angle-side abutment surface 300 b is rotated around the bolt 14 in the bolt insertion hole 17 provided at the shoe 8 a, but this deformation is received by the coupling beam portion 100 b, which leads to prevention or reduction of the deformation of the outer peripheral portion of the housing main body 11.

Third Embodiment

Next, a valve timing control apparatus according to a third embodiment of the present invention will be described with reference to FIG. 8. The present embodiment is basically similar to the first embodiment, and therefore similar functions and effects to the first embodiment will not be described below.

In the present embodiment, the coupling beam portions 100 a to 100 d are disposed at positions where the individual shoes 8 formed on the housing main body 11 and the timing pulley 1 face each other as illustrated in FIG. 8. In other words, the coupling beam portions 100 a to 100 d are provided while being arranged on outer sides in the radial directions of the individual shoes 8 as indicated by an arrow A. Such a configuration is employed for the following reason.

The bolt 14 is inserted through the bolt insertion hole 17 of each of the shoes 8, and the front plate 12, the housing main body 11, and the rear plate 13 are securely fastened. Therefore, side clearances between the vanes 22 to 25, and the front plate 12 and the rear plate 13 should be appropriately set to facilitate smooth rotations of the vanes 22 to 25 disposed inside them.

A wide side clearance increases a risk of a leak of the hydraulic oil between the advance angle oil chamber 10 and the retard angle oil chamber 9, so that the side clearances between the vanes 22 to 25, and the front plate 12 and the rear plate 13 should be narrow to the extent that prevents the leak of the hydraulic oil and allows the vanes 22 to 25 to be rotated. However, an excessive increase in a force axially tightening the bolts 14 leads to deformation of the outer peripheral portion of the housing 5, thereby resulting in contacts between the vanes 22 to 25 and the front plate 12 or the rear plate 13.

Therefore, in the present embodiment, the coupling beam portions 100 a to 100 d are disposed at the positions where the individual shoes 8 formed on the housing main body 11 and the timing pulley 1 face each other. This configuration leads to the individual shoes 8 and the coupling beam portions 100 a to 100 d located in proximity to each other, thereby increasing the mechanical strength at these portions and preventing the outer peripheral portion of the housing main body 11 from being easily deformed even with the increase in the force axially tightening the bolts 14. This effect allows the valve timing control apparatus to eliminate or reduce such a risk that the outer peripheral portion of the housing main body 11 may be deformed to bring the vanes 22 to 25 and the front plate 12 or the rear plate 13 into contact with each other.

Further, in association therewith, since the individual shoes 8 and the coupling beam portions 100 a to 100 d are located in proximity to each other, when the housing main body 11 and the coupling beam portions 100 a to 100 d are integrated with each other by the sintering, a volume increases due to the proximity between the individual shoes 8 and the coupling beam portions 100 a to 100 d, which allows the metallic powder to be loaded by a large amount, thus improving balance of a sintered density at the time of the integrated formation. As a result, the strength can be easily secured.

The coupling beam portions are each provided between the two shoes in the first embodiment and the second embodiment and provided while being arranged on the radial direction side of each of the shoes in the third embodiment, but may be provided by combing the first embodiment or the second embodiment and the third embodiment to each other.

Further, the housing includes the housing main body, the front plate, and the rear plate, but the housing main body and the front plate or the rear plate may be integrally formed into the housing main body.

In the above-described manner, according to the embodiments of the present invention, the timing pulley is disposed on the outer peripheral portion of the housing forming the advance angle oil chambers and the retard angle oil chambers with the interval, and the outer peripheral portion of the housing and the timing pulley are coupled with each other via the plurality of coupling beam portions with the interval in the circumferential direction. Further, the housing, the timing pulley, and the coupling beam portions are integrally formed from metal.

According thereto, the outer peripheral portion of the housing and the timing pulley are connected via the coupling beam portions and are integrally formed, and thus the outer peripheral portion of the housing is reinforced by the coupling beam portions, so that the outer peripheral portion of the housing can have a thin thickness.

The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail to facilitate better understanding of the present invention, and are not necessarily limited to the configurations including all of the described features. Further, a part of the configuration of some embodiment can be replaced with the configuration of another embodiment, and some embodiment can also be implemented with a configuration of another embodiment added to the configuration of this embodiment. Further, each of the embodiments can also be implemented with another configuration added, deleted, or replaced with respect to a part of the configuration of this embodiment.

The present application claims priority to Japanese Patent Application No. 2015-111184 filed on Jun. 1, 2015. The entire disclosure of Japanese Patent Application No. 2015-111184 filed on Jun. 1, 2015 including the specification, the claims, the drawings, and the abstract is incorporated herein by reference in its entirety.

REFERENCE SIGN LIST

-   1 timing pulley -   2 camshaft -   3 phase conversion mechanism -   4 hydraulic circuit mechanism -   5 housing -   6 cam bolt -   7 vane member -   8 shoe -   9 retard angle hydraulic chamber -   10 advance angle hydraulic chamber -   11 housing main body -   12 front plate -   13 rear plate -   14 bolt -   21 vane rotor -   22 to 25 vane -   100 a to 100 d coupling beam portion 

1. A valve timing control apparatus for an internal combustion engine, comprising: a timing pulley to which a rotational force is transmitted from a crankshaft via a timing belt; a housing configured to be rotated by the timing pulley and including a plurality of shoes provided on an inner peripheral surface thereof; and a vane rotor relatively rotatably contained inside the housing and configured to be rotated in synchronization with a camshaft, the vane rotor including a vane forming a retard angle oil chamber and an advance angle oil chamber inside the housing in cooperation with the plurality of shoes, wherein a predetermined interval is provided between an outer peripheral portion of the housing and an inner peripheral portion of the timing pulley, wherein an outer peripheral portion of a housing main body of the housing and the inner peripheral portion of the timing pulley are coupled with each other via a plurality of coupling beam portions with intervals in a circumferential direction, and wherein the housing main body, the timing pulley, and the plurality of coupling beam portions are integrally formed.
 2. The valve timing control apparatus for the internal combustion engine according to claim 1, wherein the housing main body is formed into a cylindrical shape opened at both ends thereof, and wherein the openings are closed by a front plate and a rear plate.
 3. The valve timing control apparatus for the internal combustion engine according to claim 2, wherein the timing pulley is disposed between projection surfaces defined by radially extending outer surfaces of the front plate and the rear plate.
 4. The valve timing control apparatus for the internal combustion engine according to claim 3, wherein the housing main body and the timing pulley are formed in such a manner that axial lengths thereof are approximately the same as each other.
 5. The valve timing control apparatus for the internal combustion engine according to claim 3, wherein the plurality of coupling beam portions is formed in such a manner that an axial length of each of them is shorter than axial lengths of the housing main body and the timing pulley.
 6. The valve timing control apparatus for the internal combustion engine according to claim 1, wherein the plurality of coupling beam portions is each formed between the plurality of shoes in a circumferential direction of the housing main body.
 7. The valve timing control apparatus for the internal combustion engine according to claim 1, wherein the plurality of coupling beam portions is formed while being arranged on a radially outer side of each of the plurality of shoes provided on the housing main body.
 8. The valve timing control apparatus for the internal combustion engine according to claim 6, wherein, between an opposite surface of each of the plurality of shoes including an abutment surface against which a stopper surface formed on the vane abuts, and each of the plurality of shoes facing the opposite surface in the circumferential direction, the plurality of coupling beam portions is each formed on one side closer to the opposite surface with respect to a center in the circumferential direction.
 9. The valve timing control apparatus for the internal combustion engine according to claim 1, wherein the timing pulley, the housing main body, and the plurality of coupling beam portions are integrally formed by sintering ferrous metallic powder.
 10. An internal combustion engine comprising: a valve timing control apparatus; and a cylinder head on which the valve timing control apparatus is mounted, wherein the valve timing control apparatus includes a timing pulley to which a rotational force is transmitted via a timing belt from a crankshaft configured to be rotated by activation of a piston, a housing configured to be rotated by the timing pulley and including a plurality of shoes provided on an inner peripheral surface thereof; and a vane rotor relatively rotatably contained inside the housing and configured to be rotated in synchronization with a camshaft configured to open and close an engine valve, the vane rotor including a vane forming a retard angle oil chamber and an advance angle oil chamber inside the housing in cooperation with the plurality of shoes, wherein a predetermined interval is provided between an outer peripheral portion of the housing and an inner peripheral portion of the timing pulley, wherein an outer peripheral portion of a housing main body of the housing and the inner peripheral portion of the timing pulley are coupled with each other via a plurality of coupling beam portions with intervals in a circumferential direction, and wherein the housing main body, the timing pulley, and the plurality of coupling beam portions are integrally formed.
 11. The internal combustion engine according to claim 10, wherein the housing main body is formed into a cylindrical shape opened at both ends thereof, wherein the housing includes a front plate and a rear plate closing the openings, and wherein the timing pulley is disposed between projection surfaces defined by radially extending outer surfaces of the front plate and the rear plate.
 12. The internal combustion engine according to claim 10, wherein the plurality of coupling beam portions is formed in such a manner that an axial length of each of them is shorter than axial lengths of the housing main body and the timing pulley.
 13. The internal combustion engine according to claim 10, wherein the timing pulley, the housing main body, and the plurality of coupling beam portions are integrally formed by sintering ferrous metallic powder.
 14. The internal combustion engine according to claim 10, wherein the plurality of coupling beam portions is each formed between the plurality of shoes in a circumferential direction of the housing main body. 